package lanqiao;

import java.util.Scanner;

/**
 * @Project : ProgrammingExercises
 * @Package : LanQiao.PrepareForCompetition
 * @File : Q2098.java
 * @Author : WangRuoyu
 * @Date 2023/3/11 14:39
 */
public class Q2098 {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        long a = scan.nextLong();
        long b = scan.nextLong();
        long n = scan.nextLong();

        long week;
        long day;
        week = n / (2 * b + 5 * a);

        n -= week * (2 * b + 5 * a);

        if (n <= 5 * a) {
            day = n / a;
            if (n % a != 0) {
                day++;
            }
            System.out.print(week * 7 + day);
        } else {
            n -= 5 * a;
            day = 5 + (n / b);
            if (n % b != 0) {
                day++;
            }
            System.out.print(week * 7 + day);
        }

        scan.close();
    }
}


